RK Racing Chain M520HD-120 520 Series 120-Link - Heavy Duty 4 Pack

Our review of the RK Racing Chain M520HD-120 4 Pack finds it best suited for riders who need a dependable, heavy-duty replacement chain for street or off-road bikes up to about 400cc. The biggest reason to buy is consistent build quality: chains in the RKM series are manufactured in Malaysia with Japanese steel, use two-point riveted pins and curled bushings, and arrive pre-stressed and pre-stretched so they run true with fewer adjustments. For the budget-conscious rider wanting a robust, factory-spec 520 chain in a convenient 4-pack, this chain delivers clear value.

Key Features

• Japanese steel construction: The chain is made with Japanese steel to meet Japanese specs, which helps ensure consistent material strength and fatigue resistance.
• Two-point riveted pins: Two-point riveting improves joint security under load and reduces the chance of pin pull-through on heavy-duty use.
• Curled bushings: Curled bushings add contact area and help distribute wear, extending usable life between replacements.
• Pre-stressed and pre-stretched: The chain arrives with initial stretch taken care of, so it needs fewer early adjustments and runs more reliably from first fitment.
• Heavy-duty tensile rating: A maximum tensile strength of 7700 pounds/ft gives a safety margin for street and NA off-road use up to the specified capacity.
• Master link clip type: The clip master link makes installation and removal straightforward for home mechanics and trackside repairs.

Who It's For

The M520HD-120 is aimed at riders of 250-400cc motorcycles and NA off-road machines who want a rugged, factory-spec 520 chain that is ready to run out of the box. It is particularly useful for DIY mechanics and small shops that appreciate the convenience of a 4-pack for multiple bikes or spare chain inventory.

Racers pushing extreme limits or owners of high-power superbikes should look for chains rated for larger displacement and higher loads; similarly, if exceptional corrosion resistance is critical for coastal or salt-exposed use, consider a chain with dedicated corrosion protection, since some users report rust issues over time.

Pros & Cons

Pros

• Made with Japanese steel and two-point riveted pins for reliable strength and joint security.
• Pre-stressed/pre-stretched construction reduces early maintenance and initial adjustment frequency.
• Good value in a 4-pack for multiple bikes or spare stock, with easy-install clip master links.
• Strong tensile rating suitable for typical street and NA off-road 400cc class use.

Cons

• Some customers report mixed durability related to rust and stretching during heavy use, so corrosion protection may be limited.
• Not intended for very high-displacement or heavily modified high-power bikes where a heavier series chain is required.

Specifications

Series	M520HD (520 Series)
Links per pack	120 links (per chain), 4 pack
Pin length	18.80mm
Pin to pin center	15.875mm
Maximum tensile	7700 pounds/ft
Weight	3.65 lb per 100 links
Master link type	Clip

Our Verdict

The RK Racing Chain M520HD-120 4 Pack is a solid, cost-effective choice for riders of up to about 400cc who need a durable, ready-to-install 520 series chain. Its Japanese-steel construction, two-point riveted pins and pre-stressed finish deliver real value for routine street and NA off-road use, though riders requiring superior corrosion resistance or higher capacity should consider alternatives. For most home mechanics and fleet owners, the 4-pack is practical and economical.

Frequently Asked Questions

Is this chain ready to install out of the box?
The chains are pre-stressed and pre-stretched, so they need fewer initial adjustments and are ready for installation with a clip master link.

What bike size is this chain suitable for?
It is intended for 520 series fitments up to about 400cc street and NA off-road applications.

How long does the chain last and does it resist rust?
Build quality is good for wear life, but some users report rust and stretching under heavy use, so regular lubrication and inspection are recommended.